First, reference is made to a general method for allocating uplink resources in a broadband wireless access system. A base station allocates resources taking into consideration a channel status (i.e., Channel Quality Information (CQI)), the amount of data delay, throughput, and Quality of Service (QoS) of each mobile terminal.
Here, a Proportionally Fairness Scheduler (PFS) is used to determine mobile terminals that will use Partial Usage of Subchannels (PUSCs) including distributed subcarriers of the OFDMA system. One frame can be divided into a number of scheduling resources. The base station sequentially performs PFS until all scheduled resources are allocated. This process is repeated every frame.
According to the PFS result, the base station can allocate one or more mobile terminals to one frame. PFS is a method used to select mobile terminals which maximizes the value obtained by dividing the maximum amount of data T_insti(t) according to a channel status at a scheduling time “t” by the average amount of actually transmitted data T_smoothedi(t) as in the following Equation 1. Here, the process of Equation 1 is not performed when there is no data to be transmitted to the mobile terminals.
                                          M            i                    ⁡                      (            t            )                          =                                            T_inst              i                        ⁢                          (              t              )                                                          T_smoothed              i                        ⁢                          (              t              )                                                          [                  Equation          ⁢                                          ⁢          1                ]            
At any scheduling instant t, the scheduling metric Mi(t) for subscriber i
The average data amount T_smoothedi(t) which is a denominator in Equation 1 is calculated each time after resources are allocated as in the following Equation 2. A parameter “TPF” in Equation 2 represents the size of a window during which the service can be maintained without receiving data. In Equation 2, the current transmission amount “T_insti” of all mobile terminals excluding mobile terminals selected at time “t” is “0”.
                                          T_smoothed            i                    ⁢                      (            t            )                          =                                            1                              T                PF                                      *                          T_inst              i                        ⁢                          (              t              )                                +                                    (                              1                -                                  1                                      T                    PF                                                              )                        *                          T_smoothed              i                        ⁢                          (                              t                -                1                            )                                                          [                  Equation          ⁢                                          ⁢          2                ]            
The following Table 1 represents QoS of various services. The Unsolicited Grant Service (UGS) is sensitive to transmission delay and the sensitivity of each service to transmission delay decreases in the order given in the table (i.e., the Best Effort (BE) is least sensitive to transmission delay).
TABLE 1Mandatory QoSServiceDefinitionApplicationsParametersUGSReal-time dataT1/E1,Max. Sustained Traffic(Unso-streamsVoIP w/oRatelicitedconsisting ofsilenceMin. Reserved TrafficGrantfixed-size dataSuppressionRateService)Packets issuedMaximum Latencyat periodicTolerated JitterIntervalsUplink Grant SchedulingTypeRequest/TransmissionPolicyUnsolicited GrantInterval(Vendor specific)rtPSReal-time dataMPEG videoMinimum Reserved TrafficstreamsRateconsisting ofMaximum Sustainedvariable-sizedTraffic Ratedata packetsMaximum Latencythat are issuedUplink Grant Schedulingat periodicTypeintervalsRequest/TransmissionPolicynrtPSDelay-tolerantFTPMinimum Reserved Trafficdata streamsRateconsisting ofMaximum Sustainedvariable-sizedTraffic Ratedata packets forTraffic Prioritywhich minimumUplink Grant Schedulingdata rate isTyperequiredRequest/TransmissionPolicyBEData streams forHTTPMaximum Sustainedwhich no MinimumTraffic Rateservice level isTraffic Priorityrequired andRequest/Transmissiontherefore may bePolicyhandled on aspace-availablebasis
Information of uplink resources allocated using the method described above is transmitted to each mobile terminal through a UL-MAP message every frame. That is, when a mobile terminal transmits uplink data to the base station, the mobile terminal must utilize multiple frames in order to transmit the entirety of the data.
In order to transmit data to the base station, the mobile terminal attempts to make an uplink allocation request (i.e., a Bandwidth Request (BR)) for the uplink. The mobile terminal can request uplink resources of up to 524,287 bytes using a BR header, a BR and UL Tx power report header, a BR and CINR report header, a BR and UL sleep control header, etc.
For example, when it is assumed that only one mobile terminal in a cell desires to receive a File Transfer Protocol (FTP) service with a mean size of 19,500 bytes or a Hypertext Transfer Protocol (HTTP) service with a mean size of 34,500 bytes, the mobile terminal must utilize multiple frames in order to transmit the entirety of data.
In addition, in the case where the cell includes a large number of mobile terminals which receive a variety of services, the mobile terminals must share resources remaining after resources are allocated to a service with QoS higher than that of FTP or HTTP. Thus, each mobile terminal will transmit data through a larger number of frames.
FIG. 1 illustrates a general method in which a Base Station (BS) allocates uplink resource regions to a mobile terminal or Mobile Station (MS).
As shown in FIG. 1, the BS allocates wireless resources to the MS through a UL-MAP message (S101). At step S101, the BS allocates a frame including a transmission region to allow the MS to transmit data to the BS.
The MS transmits data to the BS using transmission information allocated to one frame included in the UL-MAP message received at step S101 (S102).
When the MS has not yet transmitted the entirety of the data, the MS requests that the BS allocate resources to the MS and the BS then reallocates a transmission region of one frame to the MS using a UL-MAP message (S103).
The MS transmits data to the BS through the transmission region of the frame allocated at step S103 (S104) and these steps are repeated every frame until the MS transmits the entirety of the data (S105 and S106).